Caffeine is a central nervous system stimulant drug used as an aid to stay awake, for mental alertness due to fatigue, and as an adjunct with other drugs for pain relief. Caffeine is available alone as a nonprescription drug, in combination with other nonprescription drugs, and in prescription drug combinations for relief of pain and headache.

Safetychecker Summary for Caffeine
(for details about the summarized interactions, read the full article)

May be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them.	Calcium
Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	Ephedra Tobacco
Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.	Guaraná
Side effect reduction/prevention	None known
Supportive interaction	None known
Reduced drug absorption/bioavailability	None known

Interactions with Dietary Supplements

Calcium
In 205 healthy postmenopausal women, caffeine consumption (three cups of coffee per day) was associated with bone loss in women with calcium intake of less than 800 mg per day.¹ In a group of 980 postmenopausal women, lifetime caffeine intake equal to two cups of coffee per day was associated with decreased bone density in those who did not drink at least one glass of milk daily during most of their life.² However, in 138 healthy postmenopausal women, long-term dietary caffeine (coffee) intake was not associated with bone density.³ Until more is known, postmenopausal women should limit caffeine consumption and consume a total of approximately 1,500 mg of calcium per day (from diet and supplements).

Interactions with Herbs

Guaraná (Paullinia cupana)
Guaraná is a plant with a high caffeine content. Combining caffeine drug products and guaraná increases caffeine-induced side effects.

Ephedra sinica (Ma huang)
Many herbal weight loss and quick energy products combine caffeine or caffeine-containing herbs with ma huang (Ephedra sinica). This combination may lead to dangerously increased heart rate and blood pressure and should be avoided by people with heart conditions, hypertension, diabetes, or thyroid disease.⁴

Interactions with Foods and Other Compounds

Food
Caffeine is found in coffee, tea, soft drinks, and chocolate. To reduce side effects, people taking caffeine-containing drug products should limit their intake of caffeine-containing foods/beverages.

Tobacco
Smoking can increase caffeine metabolism,⁵ decreasing effectiveness. Smokers who use caffeine-containing drug products may require higher amounts of caffeine to achieve effectiveness.

References:

1. Harris SS, Dawson-Hughes B. Caffeine and bone loss in healthy postmenopausal women. Am J Clin Nutr 1994;60:573–8.

2. Barrett-Connor E, Chang JC, Edelstein SL. Coffee-associated osteoporosis offset by daily milk consumption. The Rancho Bernardo Study. JAMA 1994;271:280–3.

3. Lloyd T, Rollings N, Eggli DF, et al. Dietary caffeine intake and bone status of postmenopausal women. Am J Clin Nutr 1997;65:1826–30.

4. Tyler VE. Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York, Pharmaceutical Press, 1994, 88–9.

5. Joeres R, Klinker H, Heusler H, et al. Influence of smoking on caffeine elimination in healthy volunteers and in patients with alcoholic liver cirrhosis. Hepatology 1988;8:575–9.

Please read the disclaimer about the limitations of the information provided here. Do NOT rely solely on the information in this article.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over-the-counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2003.

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